Advances in technology have led to improvements in the precision of guided munitions. However, as guidance systems have become more sophisticated, the need for even greater precision is apparent. As military targets are frequently found in civilian surroundings, highly precise guidance systems are required to destroy these military targets while minimizing collateral damage to the civilian surroundings. One approach to increasing the precision of guided munitions is through using a laser designator to illuminate the desired target. A quadrant detector within the radome of the guided munition then guides the munition to maximize the reflected laser signal received from the illuminated target.
While such laser guided munitions have been in operation for quite some time, the radome/detector design limits the velocity of these guided munitions. In particular, many of the radome/detector designs include a hemispherical radome. The velocity of a guided munition having a hemispherical radome is limited due to the radome's aerodynamic drag. In an effort to reduce this aerodynamic drag, the use of more conic-shaped radomes has been attempted. However, this change in radome shape has created problems for the detector system used to guide the munition. Moreover, the simple quadrant detectors used in a hemispherical radome are incompatible with the optical transmission properties of a more conic-shaped radome.
Further, while laser guided munitions exist, the requirement of using a continuous laser for illuminating the target is undesirable. The use of a continuous laser creates a beacon for anti-aircraft batteries wishing to destroy the aircraft guiding the munition. For this reason, the use of a pulsed laser is desirable. This creates additional guidance problems as the guided munition receives far less reflected laser signal, resulting in the need for more accurate guidance feedback based upon this limited reflected laser signal. This requirement for accuracy in spite of limited reflected laser signal is even greater when the velocity of the guided munition increases.
An additional drawback of many laser guided munitions is the requirement for an external designator. This places the designator, for example the aircraft that released the guided munition, at risk. Given the fact that the designator must be within laser range of the target, such laser guided munitions cannot be operated in a “fire and forget” mode that minimizes risk.
A still further issue with laser guided munitions is tracking a moving target. A laser designator may lock onto a highly reflective object in the background rather than the desired moving target in the foreground. By not detecting whether an object is the desired moving target, the target itself may escape. This is especially true of certain countermeasures whose speed would not match that of a target, such as an aircraft.
Thus, a new approach for detecting an optical radiation signal that allows for greater guided munition velocities is needed that provides greater sensitivity for more accurate guidance of the munition. This new approach should be compatible with a conic-shaped radome. Further, the approach should discriminate targets from background based upon target speed by conducting angular processing after conducting Doppler processing. Lastly, the approach should be completely autonomous after the guided munition is released.